Analysis And Reinforcement Of Lateral Vibration Of Railway Simply Supported Beam Bridge Based On Deterioration

The early-stage railway bridges in China often used multi-piece prefabricated concrete simply-supported beam bridges.So far due to low design standards,aging materials,elevated line loads,complex environmental erosion,and insufficient vascular maintenance,etc.Resistance decay and lateral stiffness degradation,bury hidden dangers for traffic on the bridge.In the early bridge design,the allowable stress method was adopted.The vertical stiffness of the bridge is large,and the lateral stiffness is relatively small.The biggest problem with most old bridges today is insufficient lateral stiffness.The aging and damage of the diaphragms cause the bridge’s lateral rigidity index to exceed the limit and endanger driving safety.This paper relies on the Shaanxi Huangling Railway Dedicated Line Inspection Project to perform statistical analysis on the inspection data of all bridges on the dedicated line,evaluate the identified diseases and determine their impact on the lateral structure of the bridge,divide the primary and secondary factors according to the degree of influence,and focus on Considering the deterioration of the main beam and pier of the bridge,the influence of the different damage degrees of the diaphragm on the lateral rigidity of the bridge,the finite element and the vehicle-bridge coupling model are used to calculate and analyze the lateral response of the bridge,and an effective lateral reinforcement scheme is proposed and compared.effect.The main research contents are as follows:(1)The main types and causes of the deterioration of reinforced concrete structures were discussed,and the deterioration of 20 bridges that had been in operation for 27 years on the railway dedicated line was counted,and the actual disease situation of 32 m simple-supported beam bridges was sorted out.There are a lot of cracks in the main beam and pier of the bridge,and the surface deterioration is obvious.According to statistics,the equivalent concrete strength of the main beam and pier decreased by 14.34% and 11.60% on average.Among them,the overall damage of the wet joints accounted for 56.85% of the diaphragm damage,only The damage to the upper diaphragm accounted for 35.27%,and only the damage to the lower diaphragm accounted for 7.88%.(2)Evaluate the detection index of the 32 m bridge lateral stiffness according to the specification.It can be seen from the data that the lateral natural vibration frequency of the bridge span is lower than the normal value and higher than the safety limit;the lateral acceleration is higher than the specification limit;and although the lateral amplitude is lower than the safety limit,it exceeds the normal value.After comprehensive consideration,It is judged that the lateral rigidity of the main beam is insufficient;the lateral natural vibration frequency of the pier is much higher than the normal value,the lateral amplitude of the pier is lower than the normal value,and the pier is in good condition.(3)Establish the ANSYS finite element model,calculate and analyze the change law of the bridge’s lateral deflection and natural frequency under various inferior chemical conditions.The analysis shows that the secondary diaphragm and the end diaphragm of the bridge have a great influence on the transverse of the bridge,and the mid-span diaphragm has a small effect on the lateral of the bridge.In the three cases of diaphragm damage,the lateral The impact from large to small is as follows: overall damage,only upper damage,only lower damage.(4)The vehicle-bridge coupling model is established through UM software,and the dynamic response of the bridge and vehicles under different working conditions is calculated and analyzed.Comparing the changes of the bridge’s lateral amplitude,acceleration,vehicle comfort,and derailment coefficient at different speeds,we can get: the dynamic index response of the bridge and the vehicle is basically consistent with the results of the finite element analysis,and the wet joints of all the diaphragms of the entire bridge When the damage is overall and the thickness is reduced by half,the lateral response of the bridge is violent,which is similar to the dynamic response of the measured bridge.(5)Adhering to the principle of reasonable,economic,fast and effective reinforcement,Xshaped coplanar steel diagonal braces are selected to reinforce the bridge laterally.After the reinforcement,the first and second-order lateral natural vibration frequencies of the bridge are increased by 19.71% and 39.18% The lateral amplitude and acceleration decreased by 60.52% and 14.34%;the vertical amplitude and natural frequency increased by 1.11% and 2.51%;the vehicle derailment coefficient and comfort decreased by 34.27% and 31.60%.